The obstructed oceanview cabins on the Dawn are on Deck 8, so you're views will be great up on Deck 9.

The Dawn is a great ship for teenagers.

Yes, some of the cabins are better than others. Which is true for every cruise ship in the world. Generally speaking, the higher your cabin is on the ship, the better and more expensive it is. Which class of cabin are you thinking about booking? How many will be in your party?